The disclosures of the following priority application(s) are herein incorporated by reference:
The disclosures of Japanese Patent Application Nos. HEI 10-205982 filed on Jul. 22, 1998, and HEI 10-333885 filed on Nov. 25, 1998, including the specifications, drawings and abstracts, are incorporated herein by reference in their entirety.
1. Field of Invention
The present invention relates to an impact energy absorbing structure formed in an upper portion of a body of a motor vehicle, and to an impact energy absorbing component. More particularly, the invention relates to an impact energy absorbing structure formed in an upper vehicle body portion including a vehicle body structural member, such as a pillar, a roof side rail, a header or the like, and an interior trim, such as a pillar garnish, a roof lining or the like, that is spaced from the structural member by an interval extending toward the interior of a passenger compartment, wherein an energy absorbing member is disposed within the interval, and also relates to an impact energy absorbing component for use in the impact energy absorbing structure.
2. Description of Related Art
In motor vehicles, particularly, in passenger cars, an energy absorbing member is disposed in a space between an interior trim and a structural member of a vehicle body. Therefore, if an impact load is applied in a direction from the interior trim to the structural member, the energy absorbing member deforms to absorb energy of the impact load. Normally employed energy absorbing members are, for example, a grid rib member, a urethane pad, a steel member formed by bending a thin steel sheet so as to have a hat-like sectional shape, and the like. Also employed as an energy absorbing member is a generally-termed hybrid pipe (as described in U.S. Pat. No. 5,680,886) that is made up of a metal foil core member and sheets of a material other than metal that are laid on opposite side surfaces of the core member. In the hybrid pipe, the core member and the sheets on the opposite side surfaces of the core member are corrugated so that ridges and grooves alternate in a direction of a longitudinal axis of the pipe.
A hybrid pipe, after being formed, can easily be changed into a desired sectional shape by correspondingly shaping the pipe. Furthermore, the energy absorption characteristics of a hybrid pipe can be adjusted by changing a thickness of the hybrid pipe measured between an outermost point in the curved outer surface of a ridge or protruded portion and an innermost point in the curved inner surface of a groove or recessed portion, that is, the generally-termed apparent plate thickness of the hybrid pipe, or by changing the pitch between adjacent protruded portions (or recessed portions), or the like. Thus, a hollow-shaped energy absorbing member represented by a hybrid pipe or the like has good properties desirable for an energy absorbing member.
Vehicle body structural members to be installed at certain locations in a vehicle body are formed into three-dimensionally bent shapes in order to meet strength and design requirements. In some locations, therefore, it is difficult to dispose an energy absorbing member so as to extend precisely conforming to the shape of an adjacent structural member. Interior trims are normally formed mainly to meet design needs, and the need to conform an interior trim to a local shape of an adjacent structural member is rather minor. Therefore, if a hybrid pipe or a different hollow pipe is disposed in an interval between a structural member and an interior trim, there may be a gap formed between the structural member and the energy absorbing member or between the energy absorbing member and the interior trim, the gap extending in directions of the length of the structural member and varying in size with progress in those lengthwise directions.
An energy absorbing member preferably starts deforming during an initial period following occurrence of an impact load, and absorbs a designed amount of energy as it is displaced to a predetermined amount of displacement. However, if there is a gap between the energy absorbing member and an interior trim or a structural member, the energy absorbing member does not deform until the gap is eliminated. The aforementioned predetermined amount of displacement of an energy absorbing member means an amount of displacement to which the energy absorbing member can be displaced while being deformed by an impact load. The predetermined amount of displacement is substantially constant. Therefore, if there is a gap between the energy absorbing member and the structural member or the interior trim, an impact load will move the energy absorbing member to an amount of displacement corresponding to the size of the gap without deforming the energy absorbing member, so that the effective displacement of the energy absorbing member caused by the impact load decreases and the amount of energy absorbed correspondingly decreases. Thus, if a gap exists between an energy absorbing member and an interior trim or a structural member, and the size of the gap varies in directions of length of the structural member, the amount of energy absorbed becomes likely to greatly vary depending on the site of impact load.
Accordingly, it is an object of the present invention to provide an impact energy absorbing structure in an upper vehicle body portion that makes full use of the excellent properties of a hollow member, such as a hybrid pipe, and actually accomplishes energy absorption as designed.
It is another object of the invention to provide an impact energy absorbing component for use in an impact energy absorbing structure.
In accordance with a first aspect of the invention, an impact energy absorbing structure in an upper vehicle body portion includes a vehicle body structural member extending in a lengthwise direction, an interior trim spaced from the structural member by an interval extending inwardly from the structural member, and an energy absorbing member disposed in the interval between the interior trim and the structural member and extending along the structural member in the lengthwise direction. The energy absorbing member is formed so that a section of the energy absorbing member taken on an imaginary plane perpendicular to the lengthwise direction has a substantially uniform shape along the lengthwise direction. The impact energy absorbing structure further includes a spacer filling a gap that is formed at least either between the energy absorbing member and the structural member or between the energy absorbing member and the interior trim, at a first location along the vertical structural member.
In this impact energy absorbing structure, the energy absorbing member and the spacer are disposed in the interval between the structural member and the interior trim. The spacer may be formed in accordance with the size of the gap that is formed at least either between the energy absorbing member and the structural member or between the energy absorbing member and the interior trim, at a first location along the vertical structural member. Since the spacer substantially fills the gap, the energy absorbing member starts to undergo compression deformation substantially immediately when an impact load occurs in a direction from the interior trim to the structural member.
The spacer substantially filling the gaps makes it possible for the energy absorbing member to immediately start compression deformation and thereby absorb energy upon application of an impact load. If there is a gap, substantial energy absorption does not start until the interior trim or the energy absorbing member is displaced to fill the gap. This displacement is useless in terms of energy absorption. However, in the impact energy absorbing structure of the invention, such a useless displacement does not occur. That is, in the invention, the energy absorbing member can undergo compression deformation over the entire designed displacement upon an impact, and the amount of energy absorbable by the energy absorbing member can be made substantially consistent over the entire length of the structural member.
Furthermore, since the energy absorbing member is formed so that the cross sectional shape thereof is substantially uniform, there is no cumbersome or complicated operation required in production of the energy absorbing member. Moreover, the shape of the energy absorbing member can be simplified by selecting a suitable shape of the spacer, so that the production of the energy absorbing member is further facilitated. Further, the employment of a hollow energy absorbing member reduces the dependency of the energy absorption characteristics on the direction of an impact load on the energy absorbing member, and allows easy adjustment of the energy absorption characteristics thereof by changing the plate thickness, the apparent plate thickness or the twist pitch of the energy absorbing member.
The spacer may fill the gap between the energy absorbing member and the interior trim. For this arrangement, the spacer may be a resin-made ribbed arrangement which is provided integrally with a reverse surface of the interior trim that faces the energy absorbing member, and which is capable of absorbing energy.
In this structure, the spacer is provided integrally with the reverse surface of the interior trim, so that the step of forming the spacer as a separate member is omitted and the number of component parts required is decreased. Furthermore, since the spacer is a resin-made ribbed arrangement, it becomes possible to adjust the energy absorption characteristics of the energy absorbing member by selecting a plate thickness of the ribbed arrangement, a layout thereof, a length thereof, or the like.
The spacer may also be one of a resin-made ribbed arrangement and a foamed member, provided integrally with the energy absorbing member and capable of absorbing energy.
Therefore, the layout of the spacer can be completed merely by disposing, at a predetermined position, the energy absorbing member provided integrally with a resin-made ribbed arrangement or a foamed member, such as a urethane foam member, so that the step of mounting the spacer is omitted. Since the spacer is prepared as a component part separate from the energy absorbing member and the interior trim, the material and shape of the spacer can be freely selected. Therefore, the adjustment of the energy absorption characteristics of the energy absorbing member is further facilitated.
In the first aspect of the invention, the energy absorbing member may be an extruded metal pipe.
Therefore, the energy absorbing member can be formed into a predetermined shape by extrusion, so that productivity improves. The employment of a metal pipe as the energy absorbing member achieves a load-displacement energy absorption characteristic with sharp rising of load.
In the first aspect of the invention, the energy absorbing member may alternatively be a hybrid pipe having a core member formed from a metal foil and sheets laminated on opposite surfaces of the core member, each of the sheets being formed from a material other than metal. In the hybrid pipe, the core member and the sheets are shaped so that the hybrid pipe has protruded portions and recessed portions that are contiguous in a direction of a longitudinal axis of the hybrid pipe.
Being a hybrid pipe, the energy absorbing member becomes a light-weight member. A hybrid pipe can be formed by, for example, winding the core member and the sheets around a spindle, and serially forming protruded and recessed portions, so that high productivity can be achieved. Since a hybrid pipe can be relatively freely bent or shaped, it becomes easy to dispose the energy absorbing member so as to follow the shape of a structural member or an interior trim.
In accordance with a second aspect of the invention, an impact energy absorbing component includes an energy absorbing member formed by one of an extruded metal pipe and a hybrid pipe having a core member formed from a metal foil, and sheets laminated on opposite surfaces of the core member. Each of the sheets is formed from a material other than metal, and the core member and the sheets are shaped so that the hybrid pipe has protruded portions and recessed portions that are contiguous in a direction of a longitudinal axis of the hybrid pipe. The energy absorbing member is formed so that a sectional shape of the energy absorbing member taken on an imaginary plane perpendicular to a longitudinal axis of the energy absorbing member is substantially uniform in a direction of the longitudinal axis. The impact energy absorbing component further includes a spacer disposed at a predetermined position on the energy absorbing member.
If the energy absorbing member and the spacer are disposed at a predetermined position and suitably fastened, an impact energy absorbing structure is formed. The energy absorbing member and the spacer may be separately prepared, and separately transported to a location where an impact energy absorbing structure is needed, and separately fastened at that location. It is also possible to couple the energy absorbing member and the spacer beforehand so that the spacer assumes a predetermined position relative to the energy absorbing member, and transport the thus-formed component to a location where an impact energy absorbing structure is needed, and fasten the component at that location.
Since the cross sectional shape of the energy absorbing member is substantially uniform, the energy absorbing member can be efficiently produced. By disposing and fastening the energy absorbing member and the spacer at a predetermined position, an impact energy absorbing structure can easily be formed. The impact energy absorbing component is made up of the energy absorbing member and the spacer. Therefore, in a case where the energy absorbing member and the spacer are separately prepared, separately transported to a location where an impact energy absorbing structure is to be formed, and fastened at that location, the impact energy absorbing component can easily be disposed by adjusting the relative positions of the energy absorbing member and the spacer, even if the interval between the structural member and the interior trim varies.
In accordance with a third aspect of the invention, an impact energy absorbing structure in an upper vehicle body portion includes a vehicle body structural member extending in a lengthwise direction, an interior trim spaced from the structural member by an interval extending inwardly from the structural member, and an energy absorbing member disposed in the interval between the interior trim and the structural member and extending along the structural member in the lengthwise direction. The energy absorbing member is a hybrid pipe having a core member formed from a metal foil and sheets laminated on opposite surfaces of the core member, each of the sheets being formed from a material other than metal. The core member and the sheets are shaped so that the hybrid pipe has protruded portions and recessed portions that are contiguous in a direction of a longitudinal axis of the hybrid pipe. The hybrid pipe is formed so that a length of an outer periphery of a section of the hybrid pipe taken on an imaginary plane perpendicular to the longitudinal axis of the hybrid pipe is substantially consistent in the direction of the axis while a shape of the section of the hybrid pipe gradually changes in the direction of the axis.
The hybrid pipe is gradually shaped in such a manner that the cross sectional shape thereof gradually changes in the direction of the axis so that there is substantially no gap formed between the hybrid pipe and the structural member or between the hybrid pipe and the interior trim. Therefore, if the thus-shaped hybrid pipe is disposed at a predetermined position, substantially no gap is formed between the hybrid pipe and the structural member or between the hybrid pipe and the interior trim.
If an impact load occurs in a direction from the interior trim toward the structural member, the hybrid pipe starts to undergo compression deformation and perform energy absorption in an early period following the occurrence of the impact load. Therefore, impact energy can be efficiently absorbed.
In a case where, for energy absorption, a plurality of hybrid pipes having different sectional shapes but each having a uniform sectional shape are serially disposed adjacent to one another in the direction of length of a structural member, the energy absorption characteristics become discontinuous in the directions of length of the structural member because of gaps formed between adjacent hybrid pipes and the different sectional shapes of the hybrid pipes. However, in the invention, the hybrid pipe has a continuous configuration and is capable of reducing or curbing a sharp change in the sectional shape, so that continuous energy absorption characteristics can be achieved. That is, the impact energy absorption characteristics at a given site in a direction of length of the structural member does not greatly differ from those at different sites. Thus, approximately consistent impact energy absorption characteristics in the direction of length of the structural member can be achieved.
The hybrid pipe is formed so that while the length of the outer periphery of a section of the hybrid pipe taken on an imaginary plane perpendicular to the longitudinal axis of the hybrid pipe is substantially consistent in the direction of the longitudinal axis, the shape of the section of the hybrid pipe gradually changes in the direction of the longitudinal axis. Therefore, a hybrid pipe with a maximum cross section can be provided, and a hybrid pipe whose cross sectional shape gradually changes can easily be produced.
The hybrid pipe may be twisted about the longitudinal axis thereof.
The hybrid pipe, upon receiving an impact in a direction intersecting the longitudinal axis of the hybrid pipe, elongates in the direction of the longitudinal axis, so the apparent plate thickness thereof changes and the energy absorption characteristics change. If the hybrid pipe is twisted about the longitudinal axis thereof, the internal resistance or viscosity resistance against elongation in the direction of the longitudinal axis increases, so that an energy absorption characteristic with a sharp rising of load will be achieved. As a result, great amounts of impact energy can be absorbed with small amounts of effective displacement.
In accordance with a fourth aspect of the invention, an impact energy absorbing structure includes a center pillar supporting, at an intermediate portion thereof in a front-rear direction with respect to a vehicle body, a rail that supports a shoulder belt adjuster support movably in the up-down direction, a pillar garnish spaced from the center pillar by an interval extending inward from the center pillar, and an energy absorbing member disposed in the interval and extending along the center pillar in the up-down direction. The energy absorbing member is a hybrid pipe having a core member formed from a metal foil, and sheets laminated on opposite surfaces of the core member, each of the sheets being formed from a material other than metal. The core member and the sheets are shaped so that the hybrid pipe has protruded portions and recessed portions that are contiguous in a direction of a longitudinal axis of the hybrid pipe. The hybrid pipe has a pair of hollow energy absorbing portions that are connected to each other and that are disposed forward and rearward of the rail.
Since the center pillar is likely to receive an impact load in either one of the front-rear directions with respect to the vehicle body, it is a normal practice to dispose and fasten two energy absorbing members forward and rearward of the rail supporting the adjuster support. In this aspect of the invention, a single energy absorbing member having two energy absorbing portions is disposed, so that the operability in assembly improves and the number of component parts required is reduced.
In accordance with a fifth aspect of the invention, an impact energy absorbing component includes a hybrid pipe having a core member formed from a metal foil, and sheets laminated on opposite surfaces of the core member, each of the sheets being formed from a material other than metal. The core member and the sheets are shaped so that the hybrid pipe has protruded portions and recessed portions that are contiguous in a direction of a longitudinal axis of the hybrid pipe. The hybrid pipe is formed so that a length of an outer periphery of a section of the hybrid pipe taken on an imaginary plane perpendicular to the longitudinal axis of the hybrid pipe is substantially consistent in the direction of the axis, while a shape of the section of the hybrid pipe gradually changes in the direction of the longitudinal axis.
If the impact energy absorbing component including the hybrid pipe formed so that the length of the outer periphery of a section of the hybrid pipe taken on an imaginary plane perpendicular to the longitudinal axis of the hybrid pipe is substantially consistent in the direction of the longitudinal axis while the shape of the section of the hybrid pipe gradually changes in the direction of the longitudinal axis is disposed at a predetermined position and suitably fastened, an impact energy absorbing structure is formed.
The aforementioned hybrid pipe is formed so as to have a desired sectional shape by changing the sectional shape of a hybrid pipe having a circular sectional shape and therefore a maximum sectional area, that is, a cylindrical hybrid pipe, through a forming process. The thus-formed hybrid pipe is used to form the impact energy absorbing component. Therefore, the impact energy absorbing component can easily be produced.